1. Field of the Invention
The present invention relates to optical articles such as ophthalmic lenses and, in particular, to a method and apparatus for hard coating the optical article to increase the abrasion resistance and enhance other physical properties of the optical article. The invention provides a continuous or semi-continuous method and apparatus for hard coating optical articles which is efficient and cost-effective wherein two carriages at a time are reciprocated separately on a conveyor in uncoated lens loading and coated lens unloading sections to provide from the loading section a carriage full of uncoated lens ready for hard coating and from the unloading section a carriage full of jigs for holding lenses which carriage is ready for transfer to the lens loading section.
2. Description of Related Art
Lenses are used for a wide variety of purposes such as microscopes and other optical instruments as well as ophthalmic lenses used for eye glasses. While the present invention involves a method and apparatus for hard coating any type optical articles or lenses, the following discussion will be directed for convenience of ophthalmic lenses.
Polymeric materials (e.g., plastics) have become the material of choice for ophthalmic lenses and have replaced the more traditional glass lenses for a number of reasons. Plastic is lighter than glass and there can be great reduction in the weight of the optical product. Plastics also may be provided in a wide range of fashionable colors and gradient-density tints and production techniques have improved so that plastic lenses can be manufactured at high rates and in a more automated fashion than glass lenses. Polymeric materials also offer great improvement over glass in terms of impact resistance and high refractive index. In general, plastic lenses are now the lenses of choice in the industry.
Plastic lenses may be manufactured in a variety of ways by individual casting techniques as well as injection molding processes. Regardless of the method of manufacture, however, the plastic lenses typically require a hard coating to increase the abrasion resistance of the plastic lens. The hard coating is typically applied by dipping the lens in a liquid hard coating solution and the coating is then cured by chemical cross-linking. U.S. Pat. No. 3,956,540 to Laliberte et al. entitled xe2x80x9cMethod of Coating Articlesxe2x80x9d is directed to a method and apparatus for applying a synthetic resin coating of predetermined thickness to ophthalmic lenses. Basically, the lenses are grouped and moved along a conveyor and are subjected to an ultrasonic cleaning. The cleaned lenses pass to a destaticizing station and then to a coating station where a dip tank is rapidly raised to immerse the lenses in the solution and the tank is then lowered at a controlled rate to provide a coating of the desired thickness on each lens in a single operation. The above patent is hereby incorporated by reference.
U.S. Pat. No. 5,750,060 to Maus et al. is directed to plastic injection-compression multi-cavity molding of flash-free improved-cleanliness thermoplastic spectacle lenses which are suitable to be robotically dip coated. A molded-on tab with each pair of lenses is specially suited for manipulation by a robot and the procedure produces micro-clean hard-coated paired molded lenses made entirely within a single continuous cleanroom air enclosure surrounding the lenses without any human operators therein. This patent is also incorporated herein by reference.
Regardless of the method used for making ophthalmic lenses and whether or not the lenses are single lenses or made together with tabs, there still exists a need for an automated cost-effective method for hard coating the lenses. The hard coating method and apparatus should be capable of being used with little or no human intervention and provide an efficient and reliable method for hard coating the lenses.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a batch, semi-continuous and/or continuous method for hard coating optical articles such as ophthalmic lenses which method is cost-effective and reliable and may be automated so that little or no human intervention is required.
It is another object of the present invention to provide an apparatus for batch, continuous and/or semi-continuous hard coating of optical articles such as ophthalmic lenses which apparatus is cost-effective and reliable and requires little or human intervention to operate the apparatus.
In another object of the invention hard coated optical articles such as opthalmic lenses made using the method and apparatus of the invention are also provided.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
This invention is directed in one aspect to a method and apparatus for hard coating ophthalmic lenses which is a sequential series of steps which steps may be employed together to form a completely automated and continuous method or which steps may be performed individually to provide a batch or semi-continuous method. Basically stated, a plurality of carriages for holding lenses are used which carriages move sequentially through the system. At one point in the method one or more of the carriages from an uncoated lens loading section contain uncoated lenses secured in jigs in the carriage. These carriages are then dip coated to form a coating on the jig secured lenses. Once coated, the carriage is moved to an unloading section in which the coated lenses are removed from the carriage and the carriage moved to the lens loading section. In the lens loading and unloading sections two carriages are used in sequence in a reciprocating motion as described hereinbelow.
In general, a plurality of carriages are moved through an uncoated lens loading section, a dip coating section, a coated lens unloading section and, then after the unloading section, the carriages are moved back to the uncoated lens loading section and the method repeated. The carriages may be moved through the system in any form such as on a conveyor and the carriage comprises a structure for holding a plurality of jigs in a front-to-back relationship and also preferably in a side-by-side relationship. Thus, a typical carriage will generally hold 6 jigs in a front-to-back relationship and 6 jigs in a side-by-side relationship. This provides a total of 36 jigs which may be held in each carriage. Each jig is capable of holding a single lens so that a total of 36 lenses may be held by jigs in each carriage. The carriages, while all the same structure, have different functions at different points in the method and apparatus and the carriages as they are used in the method an apparatus may be defined as follows:
1. A xe2x80x9cfilled jig carriagexe2x80x9d means that the carriage is filled with jigs (without any lenses being secured in the jigs).
2. An xe2x80x9cempty carriagexe2x80x9d is a carriage which contains no jigs.
3. A xe2x80x9cfilled jig and uncoated lens carriagexe2x80x9d means a carriage which contains uncoated lenses secured in jigs with the carriage being filled with jigs and secured uncoated lens to the desired carriage capacity.
4. A xe2x80x9cfilled jig and coated lens carriagexe2x80x9d means a carriage which contains coated lenses secured in jigs with the carriage being filled with jigs and secured coated lens to the desired carriage capacity.
It is an important feature of the invention that the method and apparatus of the invention employ a leading empty carriage preceded by a filled jig carriage or a filled jig and coated lens carriage. In an uncoated lens loading section of the apparatus which employs an uncoated lens loading arm and an uncoated lens input conveyor or other lens loading device, a leading empty carriage is followed by a filled jig carriage. The filled jig carriage is moved adjacent the uncoated lens loading arm and the arm is manipulated to remove a single row of side-by-side jigs from the filled jig carriage. The filled jig carriage (which now contains one less row of jigs) is then moved back so that the empty carriage is now adjacent the uncoated lens loading arm. The uncoated lens loading arm is moved downward to the lens input conveyor and secures lenses in each of the jigs in the arm. The arm is then moved upward and the uncoated lens containing jigs are transferred to the empty carriage. The empty carriage (which now contains one row of lens containing jigs) is then moved forward with the filled jigs carriage and another row of jigs moved from the filled jig carriage (which is now adjacent the loading arm) to the uncoated lens loading arm. The filled jig carriage is then moved back with the empty carriage, lenses secured in the jigs and the jigs then transferred to the empty carriage (which contains one row of uncoated lens containing jigs from the previous step). This reciprocating process is repeated until the filled jig carriage is empty. At this point the empty carriage is now filled and is now a filled jig and uncoated lens carriage and the filled jig carriage is now an empty carriage. The filled jig and uncoated lens carriage is moved out of the uncoated lens loading section to a storage area or directly to a hard coating dip tank. Another filled jig carriage is then moved into the uncoated lens loading section so that there is a leading empty carriage (the previous filled jig carriage) followed by a filled jig carriage. The above loading procedure is repeated to load the empty carriage to form another filled jig and uncoated lens carriage.
A similar procedure is used in the coated lens unloading section in which a leading empty carriage is followed by a filled jig and coated lens carriage which carriage was formed when the filled jig and uncoated lens carriage was moved through the coating section to coat the lenses in the carriage. In the coated lens unloading section, the filled jig and coated lens carriage is moved adjacent to a coated lens unloading arm and a single row of side-by-side jigs containing coated lenses removed to the coated lens unloading arm from the filled jig and coated lens carriage. The coated lens unloading arm is moved downward to the coated lens output conveyor and the lenses are released from the jigs and the coated lenses are removed from the system. The jigs remain on the coated lens unloading arm and this arm is moved upward. The filled jig and coated lens carriage is moved back with the empty carriage so that the empty carriage is now adjacent the coated lens unloading arm. The jigs in the coated lens unloading arm (which do not now contain coated lenses) are then loaded onto the empty carriage. The empty carriage is moved forward so that the filled jigs and coated lens carriage is now adjacent the coated lens unloading arm. The above procedure is repeated to remove another row of jigs and coated lenses from the carriage which coated lenses are removed from the jigs and the system and the jigs then transferred to the empty carriage which is moved back adjacent the coated lens unloading arm. This procedure is repeated until all the coated lenses are removed. At this point, the empty carriage is now a filled jig carriage which is moved in the system to the uncoated lens loading section. The filled jig and coated lens carriage is now empty and will be used as described above with a preceding filled jig and coated lens carriage to remove coated lenses from the system and to fill jigs into the empty carriage to form a filled jig carriage.
As can be seen from the above, it is an important feature of the invention that a plurality of carriages be used in sequence which carriages hold either jigs, are empty, are filled with jigs and uncoated lenses secured in the jigs or filled with jigs containing secured coated lenses. As described above, during operation of the method and apparatus of the invention what is held in each carriage during loading and unloading steps is changing. The system uses a reciprocating motion in the uncoated lens loading section and the coated lens unloading section to either load lenses onto jigs in carriages in the lens loading section or to unload coated lenses from the system in the coated lens unloading section. It will be appreciated that each of the above operations whether the loading of lenses, the coating of lenses contained in carriages, or the unloading of coated lenses from the carriages may be performed individually to provide batch or a semi-continuous method and apparatus or in sequence so that a complete automated continuing method and apparatus may be used.
In another aspect of the invention a continuous method is provided for coating optical lenses comprising the steps of:
(a) providing a leading first empty carriage and preceding second empty carriage, each carriage adapted to hold a plurality of jigs containing lenses in a front-back arrangement, preferably also side-by-side, each jig adapted to hold a single lens;
(b) providing a plurality of preceding carriages each of which is filled with a plurality of jigs in a front-back arrangement, preferably also side-by-side, forming a filled jig carriage;
(c) providing an uncoated lens loading station including an uncoated lens loading arm, a lens supply, a coated lens unloading station, a coating tank, coated lens unloading arm and a coated lens removal system;
(d) positioning the filled jig carriage at the uncoated lens loading arm;
(e) removing the front side-by-side row of jigs from the filled jig carriage onto the uncoated lens loading arm;
(f) securing a lens from the lens supply in each jig in the uncoated lens loading arm forming a plurality of lens containing jigs;
(g) moving the filled jig carriage back with the second empty carriage so that the second empty carriage is in a position adjacent the uncoated lens loading arm and transferring each lens containing jig to the second empty carriage;
(h) repeating steps (d)-(g) until the filled jig carriage now is empty forming an empty carriage and the second empty carriage is full forming a filled jig and uncoated lens carriage;
(i) removing the filled jig and uncoated lens carriage from the uncoated lens loading station;
(j) coating the lenses in the filled jig and uncoated lens carriage in the coating tank forming a filled jig and coated lens carriage;
(k) moving the leading first empty carriage and filled jig and coated lens carriage to the coated lens unloading station;
(l) positioning the filled jig and coated lens carriage at the coated lens unloading arm;
(m)removing a front side-by-side row of jigs from the filled jig and coated lens carriage onto the coated lens unloading arm;
(n) removing the coated lenses from the jigs onto the coated lens removal system conveyor and removing the coated lenses from the system;
(o) moving the first empty carriage back with the filled jig and coated lens carriage so that the first empty carriage is positioned adjacent the coated lens unloading arm;
(p) transferring the jigs from the coated lens unloading arm to the first empty carriage;
(q) repeating steps (l)-(p) until the filled jig and coated lens carriage is empty forming an empty carriage and the first empty carriage is full forming a filled jig carriage;
(r) removing the filled jig carriage from the coated lens unloading section and repeating steps (l)-(p) to unload lenses from another filled jig and coated lens carriage; and
(s) repeating the above steps until all the lenses are coated.
In another aspect of the invention a method is provided for coating optical lenses comprising the steps of:
(a) providing a leading first empty carriage, the carriage adapted to hold a plurality of jigs containing lenses in a front-back arrangement, preferably also side-by-side, each jig adapted to hold a single lens;
(b) providing a plurality of preceding carriages each of which is filled with a plurality of jigs in a front-back arrangement, preferably also side-by-side, forming a filled jig carriage;
(c) providing an uncoated lens loading station including an uncoated lens loading arm, a lens supply, a coated lens unloading station, a coating tank, coated lens unloading arm and a coated lens removal system;
(d) positioning the filled jig carriage at the uncoated lens loading arm;
(e) removing the front row of jigs from the filled jig carriage onto the uncoated lens loading arm;
(f) securing a lens from the lens supply in each jig in the uncoated lens loading arm forming a plurality of lens containing jigs;
(g) moving the filled jig carriage back so that the first empty carriage is in a position adjacent the uncoated lens loading arm and transferring each lens containing jig to the second empty carriage;
(h) repeating steps (d)-(g) until the filled jig carriage now is empty forming an empty carriage and the second empty carriage is full forming a filled jig and uncoated lens carriage;
(i) removing the filled jig and uncoated lens carriage from the uncoated lens loading station;
(j) coating the lenses in the filled jig and uncoated lens carriage in the coating tank forming a filled jig and coated lens carriage;
(k) moving a leading second empty carriage and filled jig and coated lens carriage to the coated lens unloading station;
(l) positioning the filled jig and coated lens carriage at the coated lens unloading arm;
(m)removing a front row of jigs from the filled jig and coated lens carriage onto the coated lens unloading arm;
(n) removing the coated lenses from the jigs onto the coated lens removal system conveyor and removing the coated lenses from the system;
(o) moving the second empty carriage back so that the second empty carriage is positioned adjacent the coated lens unloading arm;
(p) transferring the jigs to the second empty carriage;
(q) repeating steps (l)-(p) until the filled jig and coated lens carriage is empty forming an empty carriage and the second empty carriage is full forming a filled jig carriage;
(r) removing the filled jig carriage from the coated lens unloading section and repeating steps (l)-(p) to unload lenses from another filled jig and coated lens carriage; and
(s) repeating the above steps until all the lenses are coated.
In another aspect of the invention an apparatus is provided for coating optical lenses comprising:
a filled jig carriage which contains jigs in a front-back and side-by-side configuration;
an empty carriage;
an uncoated lens loading station;
an uncoated lens loading arm;
an uncoated lens input means;
a coating section;
a coated lens unloading section;
a coated lens unloading arm;
a coated lens output means;
wherein a leading empty carriage and preceding filled jig carriage are positioned in the uncoated lens loading section with the filled jig carriage adjacent the uncoated lens loading arm wherein the uncoated lens loading arm removes a single front side-by-side row of jigs from the filled jig carriage, lenses from the lens input means (e.g., conveyor) are secured in the jigs and the filled jig carriage moved back so that the empty carriage is adjacent the uncoated lens loading arm and the lens containing jigs transferred to the empty carriage, with the above procedure being continued until the filled jig carriage is empty so that the empty carriage is now a filled jig and uncoated lens carriage which is moved out of the uncoated lens loading section and is dipped in the coating section; and
wherein after coating the lenses in the filled jig and uncoated lens carriage the carriage is now a filled jig and coated lens carriage and is moved into the coated lens unloading section with a leading empty carriage, the filled jig and coated carriage is moved adjacent the coated lens unloading arm and a single front side-by-side row of jigs and coated lenses removed from the carriage with the lenses being removed from the jigs and removed from the system using the coated lens output means (e.g., conveyor), the filled jig and coated lens carriage is then being moved back so that the empty carriage is adjacent the coated lens unloading arm and the jigs transferred onto the empty carriage from the coated lens unloading arm with the above procedure being continued until the filled jig and coated lens carriage is empty so that the empty carriage is now a filled jig carriage and is moved out of the coated lens unloading section and is ready to be used in the uncoated lens loading section.